Multi-row sealing station

ABSTRACT

The invention relates to a sealing station for sealing a cover film onto packaging trays, wherein the sealing station comprises a sealing tool and a bar chain and the sealing tool includes a tool upper part and a tool lower part. The bar chain is configured for conveying the packaging trays into the sealing tool and out of the sealing tool. The invention is characterized in that a tool lower part accommodates the packaging trays in at least a first and a second row, and that the tool lower part includes at least one lowerable supporting disc for lowering at least one of the first and second rows of packaging trays.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to German Application Number 102012006699.6 filed Mar. 30, 2012, to Albert Gabler entitled “Multi-Row Sealing Station,” currently pending, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a sealing station as well as to a method used of operating a sealing station.

BACKGROUND OF THE INVENTION

Apparatuses for sealing a cover film onto packaging trays, so-called sealing stations, are known in practice and, for example, from DE 690 03 503 T2. It is additionally known that such a sealing station normally comprises a sealing tool, including a tool upper part and a tool lower part, as well as a bar chain for conveying the packaging trays into and out of the sealing tool. The bar chain may, for example, be an arrangement along a conveyor path, which is chain guided on either side of the conveyor path, with one or a plurality of pusher rods extending transversely across the conveyor path from one chain to the other. The sealing tool is frequently configured such that it is capable of simultaneously sealing a plurality of packaging trays arranged in a single row. To this end, the bar chain and/or the sealing tool must be controlled such that none of the pusher rods of the bar chain will be located between the tool upper part and the tool lower part so that the sealing tool can be closed for executing the sealing operation.

In addition, further cases of use are known, in which the sealing tool is able to receive therein and seal twice the number of packaging trays, viz. two rows comprising each a plurality of packaging trays, simultaneously. The known, two-row sealing tools are disadvantageous insofar as, in view of the two-row arrangement of the packaging trays in the sealing tool, the equally spaced pusher rods cannot be controlled such that no pusher rod at all will be located between the tool upper part and the tool lower part of the sealing tool. This has especially a negative effect on the structural design of the sealing tool, since it is, for example, necessary to provide a centrally arranged aperture in at least one tool part so as to accommodate in said aperture the pusher rod remaining between the tool parts during closing of the tool, or since it is necessary to configure the sealing tool such that it has two separate lower parts. In addition, this also has a negative effect on the amount of cover film consumed during operation of the sealing station, since the additionally required space between the two rows of packaging trays—said space being especially conditioned by the aperture in the tool part—results in an increased amount of film waste. These cover films, which are normally provided in the form of a film web, are comparatively expensive to purchase and constitute an operating resource which is continuously needed, so that it will be important to consume the smallest possible amount of film.

EP 0 424 226 B1 discloses a further sealing station, which is capable of accommodating a row of packaging trays. The sealing station disclosed therein is provided with a lifting device for moving the lower part of the sealing tool in a vertical direction.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide an improved sealing station for sealing a cover film onto packaging trays, which, making use of means having the simplest possible structural design, achieves an increase in the performance of the sealing station and simultaneously a reduction of film waste to a minimum.

The sealing station according to the present invention is characterized in that the tool lower part of the sealing tool is configured for accommodating the packaging trays in at least a first and a second row. In addition, the tool lower part may include at least one lowerable supporting disc for lowering at least one of the first and second rows of packaging trays, i.e. the sealing tool can accommodate therein at least two rows of packaging trays simultaneously, whereby the performance of the sealing station will so to speak be twice that of a single-row sealing station. The lowerable supporting disc will here prevent the bar chain from colliding, while conveying the second row of packaging trays, with the row of packaging trays that has first been conveyed into the sealing tool.

In order to accomplish a particularly expedient structural design of the sealing tool, it may be of advantage for the tool lower part to include at least one stationary, i.e. immovable, supporting disc. Hence, not all the supporting discs of the sealing tool have to be implemented as lowerable supporting discs. Another embodiment is so conceived that the at least one lowerable supporting disc is, when seen in a conveying direction, arranged downstream of the at least one stationary supporting disc in the tool lower part of the sealing tool, i.e. the arrangement according to the present invention has the effect that the packaging trays conveyed into the sealing tool will first arrive at the stationary supporting disc and subsequently at the lowerable supporting disc. This allows the first row of packaging trays to be positioned on the at least one lowerable supporting disc before the second row of packaging trays is then arranged on the stationary supporting disc therebehind.

In order to accomplish a particularly efficient sequence of operations of the sealing station, the at least one lowerable supporting disc can be lowered from a first plane, in which the packaging trays are conveyed into the sealing tool, to a second plane extending on a lower level, and the bar chain can be moved through the sealing tool in said first plane, i.e. the lowerable supporting disc lowers the row of packaging trays to such an extent that the bar chain and in particular the pusher rods secured thereto can traverse the sealing station above the lowered packaging trays. The second row of packaging trays can thus be conveyed into the sealing tool in a particularly advantageous manner, without the pusher rods arranged upstream of the second row, when seen in the conveying direction, coming into contact with the packaging trays of the first row arranged in the sealing station.

The at least one lowerable supporting disc can be configured to carry the bottom of packaging trays. This allows a particularly simple structural design of the supporting disc, easy charging of the supporting discs with packaging trays and it also allows easy cleaning of the supporting disc.

The bar chain can be adapted to be passed between the tool upper part and the tool lower part while the at least one row of packaging trays or rather the lowerable supporting disc together with the packaging trays are in the lowered condition. This allows the sealing station to be operated in a particularly efficient manner.

A plurality of said lowerable supporting discs may be provided for one of the first and/or second rows of packaging trays. The plurality of lowerable supporting discs can then be secured to a common bar, i.e. connected to such a bar, that is capable of simultaneously carrying a plurality of supporting discs defining a row. Hence, it is not necessary to lower each individual of the lowerable supporting discs of this row separately, but a plurality of or all of the supporting discs of this row can be lowered in common. This will have an advantageous effect on the structural design of the sealing station and of the sealing tool, since only a single bar carrying the supporting discs has to be raised and lowered, respectively.

According to one embodiment, an electrically or pneumatically operable actuator is provided for lowering the at least one lowerable supporting disc. The drive of this actuator can be adapted to the rest of the sealing station so as to make operation of the sealing station as simple and as economical as possible.

According to a further embodiment, the sealing tool can be configured for receiving therein and/or lowering and/or sealing three, four or more rows of packaging trays simultaneously. The present invention can thus be used for increasing the efficiency of the sealing station still further.

The sealing station according to the present invention can be used in a packaging plant which may also comprise other packaging machines.

The method used according to one embodiment of the present invention for operating a sealing station comprises the following method steps:

-   -   conveying a first row of packaging trays in a first plane by         means of a bar chain into a sealing tool,     -   accommodating the first row of packaging trays on at least one         lowerable supporting disc,     -   lowering the first row of packaging trays from the first plane         to a second plane extending on a lower level by lowering the at         least one lowerable supporting disc,     -   conveying a second row of packaging trays into the sealing tool,         said second row being accommodated on a further supporting disc,     -   lifting the first row of packaging trays from the second plane         to the first plane, and     -   sealing the first and second rows of packaging trays with a         cover film.

The advantage of the method according to the present invention is that, due to the lowering of the first row of packaging trays which is already accommodated in the sealing tool, the second row of packaging trays can be introduced in the sealing tool by means of the bar chain with a minimum distance between the first and second rows of packaging trays, since the lowering of the first row of packaging trays allows the bar chain and the pusher rods secured thereto to be moved across the lowered first row of packaging trays, which means that an additional aperture in the sealing tool between the two rows of packaging trays will not be necessary. The method according to the present invention thus allows the cover film waste to be reduced to a minimum and, simultaneously, it allows an increase in the performance of the sealing station in comparison with a single-row sealing station.

According to one embodiment of the method, the bar chain is moved temporarily in a direction opposite to the conveying direction of the packaging trays so as to allow lowering of the lowerable supporting disc. This may be of advantage when the packaging trays have on the upper side thereof outwardly projecting edges used for the purpose of sealing the cover film. The bar chain or rather the pusher rods of the bar chain can thus be moved away from the packaging trays to such an extent that it will be possible to lower the lowerable supporting disc. Likewise, it will be advantageous when the bar chain is moved temporarily in a direction opposite to the conveying direction of the packaging trays so as to allow closing of the sealing tool.

In order to optimize the sequence of operations in the sealing station still further, it may be of advantage for the bar chain to be moved through the sealing tool above the second plane while the lowerable supporting disc is located in the second plane (which extends on a lower level). In particular, the bar chain can be moved through the sealing tool in the first plane, i.e. the conveying plane, thus avoiding a complicated deflection of the bar chain into different planes.

A particularly significant increase in the machine efficiency of the sealing station will be achieved, in comparison with a single-row sealing station, when the method step of sealing the packaging tray with a cover film additionally comprises evacuating and/or gas flushing, since, as regards evacuation and gas-flushing cycle times, the two- or multi-row arrangement within the sealing tool will produce an effect that is even more advantageous than that produced in cases where the packages are only sealed.

Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawing, which forms a part of the specification and is to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views:

FIG. 1 is a schematic side view of a sealing station according to one embodiment of the present invention,

FIG. 2 is a schematic side view of the sealing station according to one embodiment of the present invention with a lowerable supporting disc at a lowered position,

FIG. 3 is a schematic side view of the sealing station according to one embodiment of the present invention during conveyance of a first row of packaging trays into the sealing station,

FIG. 4 is a schematic side view of the sealing station according to one embodiment of the present invention in which the first row of packaging trays is just being received,

FIG. 5 is a schematic side view of the sealing station according to one embodiment of the present invention after reception of the first row of packaging trays,

FIG. 6 is a schematic side view of the sealing station according to one embodiment of the present invention after lowering of the first row of packaging trays and during conveyance of the second row of packaging trays into the sealing station,

FIG. 7 is a side view of the sealing station according to one embodiment of the present invention with two filled rows of packaging trays before or after sealing,

FIG. 8 is a schematic side view of the sealing station according to one embodiment of the present invention after sealing during discharge of the sealed packaging trays, and

FIG. 9 is an alternative embodiment of the sealing station comprising more than two rows of packaging trays.

Identical components are designated by identical reference numerals throughout the figures.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.

The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

FIG. 1 shows a schematic side view of a sealing station 1 according to one embodiment the present invention. The sealing station 1 is often a part of a packaging plant 100, which is here only shown in a highly schematized fashion and outlined by a broken line. The sealing station 1 serves to seal a cover film 2 onto preformed packaging trays 3 so as to protect the content of the packaging trays 3. When foodstuffs are packaged, the packaging trays 3 are evacuated and/or subjected to gas flushing before they are closed so as to guarantee a long durability of the respective foodstuff. The packaging trays 3 may, for example, be yogurt cups or other sealable plastic containers. The cover film 2 is normally provided in the form of a thermoplastic film web, which is unwound from a first roll 4 and wound onto a second roll 5 as residual film grid. The rolls 4, 5 enclose the sealing station 1 between them. The sealing station 1 additionally includes a sealing tool 6 comprising a tool upper part 7 and a tool lower part 8. The cover film 2 is passed between the tool upper part 7 and the tool lower part 8.

For conveying the packaging trays 3, the sealing station additionally includes a conveying device 9, comprising a first conveying surface 10 and a second conveying surface 11. The first conveying surface 10 is arranged upstream of the sealing tool, when seen in a conveying direction R, and the second conveying surface 11 is arranged downstream of the sealing tool 6 in said conveying direction R. The conveying device 9 may comprise a bar chain 12 including spaced-apart pusher rods 13 for driving the packaging trays 3.

It can easily be seen that the sealing tool 6 is configured for receiving therein the packaging trays 3 in a first row 14 and in the second row 15 simultaneously. The first and second rows 14, 15 may each consist of one, two, three or more packaging trays 3 extending into the drawing plane in juxtaposition, i.e. the first and second rows 14, 15 are not defined along the conveying direction R, but extend into the drawing plane.

Furthermore, it can easily be seen that the sealing tool 6 can include in its lower tool part 8 a lowerable supporting disc 16 receiving thereon and supporting the bottom of the packaging trays 3 of the first row 14. For raising and lowering the supporting disc 16, the sealing tool 6 may be provided with a pneumatically or electrically operable actuator 17, which moves the supporting disc 16 up and down in a vertical direction. A further stationary, i.e. immobile supporting disc 18, used for receiving thereon the second row 15 of packaging trays 3, can be arranged upstream of (i.e., in FIG. 1 on the right-hand side of) the lowerable supporting disc 16 when seen in the conveying direction R. Ideally, the two supporting discs 16, 18 are arranged in the tool lower part 8 at the smallest possible distance from one another so as to restrict the cover film waste to the least possible amount.

FIG. 2 shows the sealing station 1 according to one embodiment of the present invention in a schematic side view and in particular the lowerable supporting disc 16 at a lowered position. The figure shows particularly clearly that the supporting disc 16 has been lowered by means of the actuator 17 from a first plane, defined by the conveying device 9, to a second plane 19 extending on a lower level relative to the first plane. The second plane 19 and the downstroke of the actuator 17 are chosen such that the pusher rods 13 of the bar chain 12 can be moved between the tool upper part 7 and the tool lower part 8 and especially across the lowered packaging trays 3 of the first row 14.

Operation of the sealing station 1 according to the present invention can be described as follows hereinbelow.

FIG. 3, in which the sealing station 1 according to one embodiment of the present invention is shown in a schematic side view, shows clearly how the first row 14 of packaging trays 3 is conveyed into the sealing tool 6 by one of the pusher rods 13. It can also be seen that a further pusher rod 13, which constitutes part of the bar chain 12 and which is arranged downstream of said first pusher rod when seen in the conveying direction R, conveys a further, i.e. the second row 15 of packaging trays 3, in the direction of the sealing tool 6.

FIG. 4 shows the sealing station 1 according to FIG. 3 at a position at which the first row 14 has been received on the lowerable supporting disc 16. The second row 15 of packaging trays 3 is located downstream of said first row 14 in the conveying direction R.

At the position of the sealing station 1 shown in FIG. 5, the bar chain 12 has, in comparison with the position shown in FIG. 4, been moved back in a direction opposite to the conveying direction R to such an extent that the pusher rod 13, which conveyed the first row 14 of packaging trays 3 to the lowerable supporting disc 16, has detached from the packaging trays 3 of the first row 14 and is now spaced from said packaging trays 3 and the projecting edges arranged on the upper side of the packaging trays 3 to such an extent that the first row 14 of packaging trays can be lowered in the way shown in FIG. 6. FIG. 6 also shows clearly that the pusher rod 13, which previously conveyed the first row 14 of packaging trays to the supporting disc 16, has now traversed the first row 14. In the meantime, the subsequent pusher rod 13 conveys the second row 15 of packaging trays 3 to the second supporting disc 18. The next step, which is not shown in the figures, is that the pusher rods 13 which may perhaps be arranged between the tool upper part 7 and the tool lower part 8 are moved to a position outside the sealing tool 6 by a movement in a direction opposite to the conveying direction R.

FIG. 7 shows the sealing station 1 according to one embodiment of the present invention at a position at which the supporting disc 16 has been returned to the conveying plane by means of the actuator 17 so that both rows 14, 15 of packaging trays 3 are now arranged at a small distance from one another within the sealing tool 6. The sealing tool 6 is now closed and all the packaging trays arranged in said sealing tool 6 are sealed with the cover film 2 in one operating cycle, the packaging trays 3 being, if necessary, also evacuated and subjected to gas flushing in a preceding operating cycle. In addition, a tray reception unit 21 may optionally be provided for accommodating the edges of the packaging trays 3 located in the sealing tool 6 and for lifting them in the direction of the cover film 2 and/or the tool upper part 7 in an upward movement. For the purpose of sealing, pressure can then be applied to the edges of the packaging trays 3 between the tray reception unit 21 and the tool upper part 7. When such a liftable tray reception unit 21 is provided, the upward movement of the at least one supporting disc 16 can take place independently of the upward movement of the packaging trays 3 and can e.g. be executed only during the sealing step.

FIG. 8 shows the sealing station 1 at a position at which the first and second rows 14, 15 of packaging trays have been pushed together by one of the pusher rods 13 so that the packaging trays 3 can be conveyed out of the sealing tool 6 in common.

Starting from the above described embodiment, the sealing station 1 according to the present invention can be modified in many ways. The sealing station 1 may, for example, be configured such that the sealing tool 6 encloses a further row 20, as shown in FIG. 9. In order to allow the above described method of operating the sealing station 1 to be applied analogously to this embodiment, also the additional row 20 of packaging trays 3 is provided with one or a plurality of additional, lowerable supporting discs 17. The higher the number of additional rows of packaging trays 3 to be accommodated simultaneously in the sealing tool 6, the larger the distances between the individual pusher rods 13 will have to be.

From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting.

The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow. 

What is claimed is:
 1. A sealing station for sealing a cover film onto packaging trays, the sealing station comprising: a sealing tool including a tool upper part and a tool lower part, the lower tool part being configured for accommodating the packaging trays in at least a first row and a second row, the lower tool part including at least one lowerable supporting disc for lowering at least one of the first and second rows of packaging trays; and a bar chain configured for conveying the packaging trays into the sealing tool and out of the sealing tool.
 2. A sealing station according to claim 1, wherein the tool lower part additionally includes at least one stationary supporting disc.
 3. A sealing station according to claim 1, wherein the at least one lowerable supporting disc is lowered from a first plane, in which the packaging trays are conveyed into the sealing tool, to a second plane extending on a lower level, and wherein the bar chain is movable through the sealing tool in said first plane.
 4. A sealing station according to claim 1, wherein the at least one lowerable supporting disc carries the bottom of the packaging trays.
 5. A sealing station according to claim 1, wherein the bar chain is adapted to be passed between the tool upper part and the tool lower part while the at least one row of packaging trays is in the lowered condition.
 6. A sealing station according to claim 1, wherein a plurality of lowerable supporting discs are provided for lowering at least one of the first and second rows of packaging trays, and wherein the plurality of lowerable supporting discs is connected to a common bar carrying the supporting discs.
 7. A sealing station according to claim 1, wherein at least one electrically or pneumatically operable actuator is provided for lowering the at least one lowerable supporting disc.
 8. A sealing station according to claim 1, wherein the sealing tool is configured for receiving therein and sealing three or more rows of packaging trays simultaneously.
 9. A sealing station according to claim 1, wherein the sealing station is configured for use with a packaging plant.
 10. A method of operating a sealing station, said method comprising the following steps: conveying a first row of packaging trays in a first plane by means of a bar chain into a sealing tool; accommodating the first row of packaging trays on at least one lowerable supporting disc; lowering the first row of packaging trays from the first plane to a second plane extending on a lower level by lowering the at least one lowerable supporting disc; conveying a second row of packaging trays into the sealing tool, said second row being accommodated on a further supporting disc; lifting the first row of packaging trays from the second plane to the first plane; and sealing the first row and second rows of packaging trays with a cover film.
 11. A method according to claim 10, wherein the bar chain is moved temporarily in a direction opposite to a conveying direction of the packaging trays so as to allow lowering of the lowerable supporting disc.
 12. A method according to claim 10, wherein the bar chain is moved temporarily in a direction opposite to a conveying direction of the packaging trays so as to allow closing of the sealing tool.
 13. A method according to claim 10, wherein the bar chain is moved through the sealing tool above the first plane while the lowerable supporting disc is located in the second plane.
 14. A method according to claim 10, wherein the sealing of the packaging trays with a cover film additionally comprises at least one of evacuating and gas flushing. 